/*******************************************************************************

      ---------========= DSx86 Configuration Editor =========---------
                               by RyouArashi
                        http://ryouarashi.blogspot.com


              ---------========= License Agreement =========---------

Copyright 2010 RyouArashi. All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY RyouArashi ``AS IS'' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
EVENT SHALL RyouArashi OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*******************************************************************************/

/*******************************************************************************
 * Read Scan Codes from Keyboard
 ******************************************************************************/

#include <dos.h>

#include "INT09.H"

/* Win32 Filter */
static unsigned char Win32Filter = 0;

/* Get Scan Code */
unsigned GetScanCode()
{
  /* Extended Scancode Flag */
  unsigned char HasE0 = 0;
  /* Temp Scancode */
  unsigned char C;  

  void interrupt (far *OldInt09)();

  /* Backup INT09 Handler */
  OldInt09 = getvect(9);

  /* Reset ScanCode FIFO*/
  Int09RD = 0;
  Int09WR = 0;

  /* Install new INT09 Hanlder */
  setvect(9, Int09Handler);

  /* Wait for KeyPress */
  while (1)
  {
    /* Wait */
    if (Int09RD == Int09WR) continue;
    
    /* Get Code */
    C       = Int09FIFO[Int09RD];
    Int09RD = (Int09RD+1) & 0x0F;
    
    /* Extended Code */
    if (C == 0xE0) 
    {
      HasE0 = 1;
      continue;
    }
    
    /* Skip Release */
    if (C & 0x80) 
    {
      HasE0 = 0;
      continue;
    }
    
    /* Win32 Compatibility Mode*/
    if (Win32Filter)
    {
      /* Win32 throws in 0xE02A Scancodes on certain occasions, so drop them */
      if (HasE0 && C == 0x2A)
      {
        HasE0 = 0;
        continue;
      }
    } 
    
    /* Any other Code */
    break;
  }

  /* Restore old INT09 Hanlder */
  setvect(9, OldInt09);

  /* Return */
  return HasE0 ? (0xE000 | C) : C;
}

void EnableWin32Filter()
{
  Win32Filter = 1;
}

/* End of File ****************************************************************/